// 名稱空間

using System.IO;

1、一次性讀取所有行：

string [] _lines = File.ReadAllText("Txt檔案路徑");

2、按行讀取所有行：

using (FileStream fileStream = new FileStream("Txt檔案路徑", FileMode.Open, FileAccess.Read, FileShare.ReadWrite))

{

if (fileStream.CanRead)

{

StreamReader streamReader = new StreamReader(fileStream, System.Text.Encoding.Default);

string _line = streamReader.ReadLine();

while (_line != null)

{

_line = streamReader.ReadLine();

}

streamReader.Close();

}

}